Gavin, T., 3rd, D., and S. Hambridge, "How to Advertise Responsibly Using E-Mail and Newsgroups or - how NOT to $$$$$  MAKE ENEMIES FAST!  $$$$$", RFC 3098, DOI 10.17487/RFC3098, April 2001, <https://www.rfc-editor.org/info/rfc3098/>.